Chronic obstructive pulmonary disease (COPD) is a term which refers to a large group of lung diseases which can interfere with normal breathing. It is estimated that 11% of the U.S. population has COPD and the incidence is increasing. The two most important conditions covered by COPD are chronic bronchitis and emphysema.
Chronic bronchitis is a long-standing inflammation of the bronchi which causes increased production of mucous and other changes. The patients' symptoms are cough and expectoration of sputum. Chronic bronchitis can lead to more frequent and severe respiratory infections, narrowing and plugging of the bronchi, difficult breathing and disability.
Emphysema is a chronic lung disease which affects the alveoli and/or the ends of the smallest bronchi. The lung loses its elasticity and therefore these areas of the lungs become enlarged. These enlarged areas trap stale air and do not effectively exchange it with fresh air. This results in difficult breathing and may result in insufficient oxygen being delivered to the blood. The predominant symptom in patients with emphysema is shortness of breath.
At present moderate to severe COPD is treated with a variety of monotherapies including inhaled or orally administered bronchodilators, inhaled anti-cholinergic agents and orally administered steroids, especially corticosteroids. The problem with these treatments is that none of them is especially effective. For example, many patients with COPD have a reversible component. Accordingly a new treatment is required for decreasing the intensity of exacerbations, thereby improving the lung function of patients suffering from COPD.